Mediterranean Diet + Nuts = Reversal of Metabolic Syndrome
An article published yesterday by Bloomberg.com presents results of a recent scientific study in Spain that showed reduction in “metabolic syndrome” by the Mediterranean diet supplemented with nuts. CBSnews.com, Reuters, and others helped spread the news. The Bloomberg article was written by Nicole Ostrow.
Metabolic syndrome is a constellation of clinical factors that are associated with increased risk of type 2 diabetes and atherosclerotic complications such as heart attack and stroke. [Sometimes metabolic sydrome is called Syndrome X, which I sorta like. Oh, the mystery!] One in six Americans have the syndrome. Diagnosis requires at least three of the following five conditions:
- High blood pressure (130/85 or higher, or using a high blood pressure medication)
- Low HDL cholesterol: under 40 mg/dl in a man, under 50 in a women (or either sex taking a cholesterol-lowering drug)
- Triglycerides over 150 mg/dl (or taking a cholesterol-lowering drug)
- Abdominal fat: waist circumference 40 inches or greater in a man, 35 inches or greater in a woman
- Fasting blood glucose over 100 mg/dl
The scientific study at hand is part of the PREDIMED study being conducted in Spain. For this portion of the study, 1,224 participants at high risk for cardiovascular disease were randomized to follow a 1) low-fat diet (considered the control group), 2) Mediterranean diet plus 1 liter virgin olive oil per week, or 3) Mediterranean diet plus 30 gm daily of mixed nuts.
Note that the nuts used in this study were walnuts, almonds, and hazelnuts. Half of all nuts were walnuts; a quarter of the nuts were almonds and a quarter were hazelnuts.
Participants were 55-80 years old, and 61% had metabolic syndrome at baseline. Participants could eat all they wanted, and there was no increase in physical activity for any of the groups. Participants were given instructions at baseline and quarterly.
After one year of intervention, the prevalence of metabolic syndrome was reduced by 14% in the Mediterranean diet plus nuts group compared to the control, low-fat diet group. The Mediterranean diet plus extra olive oil group reduced prevalence of metabolic syndrome by 7%, but this did not reach statistical significance (P=0.18).
New cases of metabolic syndrome continued to develop at about the same rate in all three groups. I.e., incident rates were not significantly different. So, the lower prevalence of metabolic syndrome after one year reflected reversion or clearing of the syndrome in many people who had it at baseline. Compared to the control group, people in the nutty group were 70% more likely to resolve their metabolic syndrome. Individuals in the oily group were 30% more likely than controls to resolve the condition.
[Feel free to consult a dictionary for definitions of “prevalence” and “incidence.”]
The researchers conclude that:
A traditional Mediterranean diet enriched with nuts could be a useful tool in the management of the metabolic syndrome.
My Comments:
Thirty grams (daily) of nuts is a decent-sized snack of about 180 calories. Thirty grams of almonds formed a heap in the palm of my hand, not touching my fingers. This is more than the “two tablespoons” reported by CBSnews.com December 9.
If you have metabolic syndrome, you might want to try reversing it with all the usual methods (e.g., lose excess fat weight, exercise more) along with a traditional Mediterranean diet enriched with 30 gm of mixed nuts daily. As usual, check with your personal healthcare provider first. Be aware that many of them won’t know about this study.
The puzzling thing to me is: If the Mediterranean diet plus extra nuts is so effective in reversing metabolic syndrome, why didn’t that study cohort see fewer new cases of metabolic syndrome?
Steve Parker, M.D., author of The Advanced Mediterranean Diet
Additional reference: Salas-Salvado, Jordi, et al. Effect of a Mediterranean Diet Supplemented With Nuts on Metabolic Syndrome Status: One-Year Results of the PREDIMED Randomized Trial. Archives of Internal Medicine, 168 (2008): 2,449-2,458.
December 10th, 2008 at 9:56 pm
doesn’t the mediterranean diet already include a lot of nuts?
and also, 1 liter of extra olive oil per week in one of the intervention groups????? does that seem insane to anyone but me?
December 11th, 2008 at 9:23 am
Very perceptive, Darya. Thanks for your comments.
The traditional Mediterranean diet indeed includes ‘generous amounts’ of nuts, and olive oil as the predominant form of dietary fat. I’m sure consumption of the two components varied across the region, perhaps dramatically.
The PREDIMED researchers are trying to quantify a specific amount of these two foods that confer the health benefits, if any. Proponents of the Mediterranean diet can easily toss off a recommendation to “start eating nuts” or “eat more nuts.” Health conscious people need a more specific recommendation, especially since nuts can be fattening if eaten to excess.
The medical literature had already established that the heart-healthy amount of nut consumption is at least three to five 1-ounce servings of nuts weekly. An ounce is about a quarter cup, or 28.35 grams. Hey, I just figured out why these researchers chose 30 grams as their nut supplement!
Regarding the liter per week of olive oil…. That’s 8079 calories, or over 1000 calories daily for an individual! I bet that liter was for household consumption. I don’t know average household size in Spain. If we assume it is four, then average individual intake would be 288 cals daily, or 2.3 tablespoons. Much more reasonable, eh?
I think olive oil does confer health benefits. In my Advanced Mediterranean Diet book (for weight loss), I felt compelled to recommend a specific amount of intake to my readers: seven to 14 tablespoons weekly during the weight-loss phase of weight management. A little more as one enters the “maintenance of weight loss” phase. So, I’m in line with these researchers.
Again, I’m not sure it’s helpful to just tell someone, “Eat more olive oil.”
Truth is, it’s not entirely clear what is the optimal amount of olive oil for health. The PREDIMED study will help clarify this. It’s a huge study, with final reports due in 2010 or 2011.
-Steve
December 11th, 2008 at 4:24 pm
As for the lack of prevention vs the reducing of metabolic syndrome, my guess would be simple odds. Any study where several different things are being measured in a complex system like an animal body the results will be mixed. That is why we like to see studies repeated over and over, to even out mere chance as a factor.
It does seem odd to me that low-fat is used as the control. Low fat is a pretty severe change in most people’s diets. A more useful control would be something closer to the norm, 30-40% fat calories.
December 11th, 2008 at 10:37 pm
Thanks for you comments, tom. You may be right.
-Steve
February 27th, 2009 at 9:58 pm
I recommend this way of eating for many clients who come to me for health advice - all notice a change in the way they feel. Feeling good = better health. A big issue for me is the fact that getting people to eat the right stuff means they have no space left over for the wrong stuff. And I agree with the 2 Tabelespoons of Oilive Oil a day but that is total intake ie in cooking and as a dressing on cold or hot veg or even on cereal. The nuts are a fantastic way to boost essential fatty acids, get good quality protein and provide the feeling of snacking without the fat and poor nutrition normally associated with snacking. Finally we are talking about raw unsalted preferrably straight out of the shell nuts here, not roasted bar nuts!! Thanks for the blog.
February 28th, 2009 at 9:41 am
Thanks for your comments, Shayne.